JPH0247167B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bus protection relay device for protecting a power system.

Conventionally, there has been a device of this type as shown in FIG. In Figure 1, 1-1 is the bus line, 2-1
~2-5 is the line connected to bus 1-1, 3-1
~3-5 are current transformers installed in lines 2-1 to 2-5, and 4-1 to 4-5 convert the outputs of current transformers 3-1 to 3-5 into signals at appropriate levels. Conversion circuit, 5
performs addition of signals of conversion circuits 4-1 to 4-5,
A differential circuit (hereinafter referred to as an adder circuit) that obtains a differential output, 6 is a level detection circuit that determines whether the output of the adder circuit 5 is at a predetermined level, and supplies a signal to a protection relay (not shown). .

Explain the operation. The differential output, which is the sum of the currents flowing into and out of the bus 1, is zero during normal operation without any accidents, so the output of the adder circuit 5, which is a differential output, is zero. . In this state, the level detection circuit 6 does not output a signal.
However, there is a ground fault as shown on bus 1-1.
When F _A occurs, the fault current I _A flows through the current transformer 3-1 as shown by the arrow in the figure, so the output of the adder circuit 5 no longer has zero content, and the level detection circuit 6
outputs a signal.

On the other hand, there is a ground fault on track 2-4 as shown in the diagram.
When F _B occurs, fault current I _B flows through current transformers 3-1 and 3-4, so their outputs cancel each other out, so the output of adder circuit 5 becomes zero, and the level The detection circuit 6 does not output a signal. In other words, the ground fault F _B is determined to be an external fault, and the device does not activate the protective operation.

By the way, in general, not only is there a single bus bar as shown in Fig. 1, but a plurality of bus bars are connected as shown in Fig. 2, and a bus protection relay device is provided for each bus bar. . In Figure 2, 1-2 is the bus line, and 2-6 to 2-8 are the bus lines 1-
Lines connected to 2, 3-6 to 3-8 are lines 2-
Current transformers installed at 6-2-8, 3-9, 3-1
O is a current transformer installed on busbars 1-1 and 1-2, 7
-1 is a circuit breaker that connects bus bars 1-1 and 1-2.

Generally, when there is a bus connection as shown in Figure 2, current transformers 3-9, 3-
It is necessary to provide 10. In this case, the current transformer 3-10 is connected to the bus protection relay device on the bus 1-1 side, and the current transformer 3-9 is connected to the bus protection relay device on the bus 1-2 side. Bus bar 1-1, bus bar 1-2 regardless of whether vessel 7-1 is on or off.
Each will have its own protection. However, in buses with voltage levels below high voltage, the current transformers 3-9, 3-10 are often omitted.

In such a case, if a ground fault F C occurs on bus 1-2 or a ground fault F _D occurs on line 2-7 while circuit breaker 7-1 _is not shut off, bus 1
Since the bus protection relay device No.-1 does not have the current transformer 3-10, it is determined that the fault is on the bus 1-1 side, as is clear from the explanation of the ground fault F _A above. Furthermore, the busbar protection relay device installed for busbar 1-2 has a similar configuration to that of busbar 1-1, but since there is no current transformer 3-9, ground faults can occur.
F _C could not be detected, and the ground fault F _D was detected on bus 1-2.
It is determined that the problem is internal.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and even when a current transformer is not provided at both ends of a bus-coupled circuit breaker in a power system where a plurality of bus bars are connected, An object of the present invention is to provide a busbar protection relay device that can appropriately respond to a ground fault occurring on each busbar.

Hereinafter, a busbar protection relay device according to an embodiment of the present invention will be explained with reference to the block diagram of FIG.
The busbar protection relay device shown in FIG. 3 is configured to protect region B of the power system as shown in FIGS. 4a to 4c.

This power system consists of connecting bus bars 1-1, 1-2, and 1-3, and each bus protection relay device sets areas A, B, and C indicated by dotted lines in the figure as areas to be protected, respectively. Currents I _A1 to I _Ao , I _B1 to I _Bo , and I _C1 to I _Co of each circuit are detected from areas A, B, and C by current transformers (not shown).

In Fig. 3, 8-1 is a summation circuit provided in a bus protection relay device in area A (not shown) which adds current ΣI _A , which is the sum of currents I _A1 to I _Ao , when circuit breaker 7-1 is on. The switch to be introduced, 8-2, sends the current ΣI C, which is the sum of the current I _C1 I _Co, to the circuit breaker _7- by an adder circuit provided in the bus protection relay device in area C (not shown).
The switch that introduces when 2 is on, 9-1 is the current
Addition circuit that adds I _B1 to I _Bo and obtains current ΣI _B , 9-
2 is an addition circuit that adds current ΣI _A through switch 8-1 and current ΣI _B to obtain current ΣI″ _B ; 9-3 adds current ΣI _B and current ΣI _C through switch 8-2. 9-4 is an addition circuit that adds the current ΣI _A through the switch _8-1 , the current ΣI _B , and the current I _C through the switch 8-2 to obtain the current ΣI′ _B. The circuit 10 is a level detection circuit that outputs an output when the current _ΣI'B , which is the output of the adder circuit 9-4, is above a predetermined level.

The operation will be explained below.

(i) The operation when both circuit breakers 7-1 and 7-2 shown in FIG. 4a are cut off will be explained. In this case, bus bars 1-1, 1-2 and 1-
3 exist independently, and the operation is similar to that of the conventional device. That is, switches 8-1 and 8-2 are both turned off, and only the current ΣI _B of area B is input to adders 9-2, 9-3, and 9-4, and accordingly, the above-mentioned take action.

(ii) The circuit breaker 7-1 shown in Figure 4b is turned on, and the circuit breaker 7
The operation when -2 is off is explained. Now, the fourth
As shown in Figure b, if a ground fault F _B occurs in area B, the current ΣI _A seen by the bus protection relay device in area A is ΣI _A = I _B , and the current seen by the bus protection relay device in area B is The current ΣI _B is ΣI _B =−I _B .

Therefore, since the switch 8-1 on the ΣI _A side is on, the current ΣI' _B output from the adder circuit 9-4 becomes ΣI' _B =I _B -I _B =0, and the current ΣI' B output from the level detection circuit 10 does not output a signal. That is, in this case, it is determined that there is an external failure, and the busbar protection relay device in area B does not activate the protective operation.

In addition, in the bus protection relay device in area A, the current ΣI''' _B of the adder circuit 9-3 supplied from the bus protection relay device in area B to the bus protection relay device in area A is Since switch 8-2 on the ΣI _C side is disconnected, ΣI″′ _B = −I _B +0
= −I _B. This value is passed from the bus protection relay device in area B to the bus protection relay device in area A,
Therefore, the busbar protection relay device in area A is also I _B −I _B
= 0, it is regarded as an external failure, and it does not operate.

In the case of a ground fault F _A , the bus protection relay device in area A has ΣI _A =I _A and the bus protection relay device in area B has ΣI _B =0. Therefore, the adder circuit 9-4
The current ΣI′ _B becomes ΣI′ _B = I _A , and the level detection circuit 1
0 outputs a signal. In other words, the device is considered to have an internal failure.

In addition, since ΣI''' _B = 0 in the bus protection relay device in area A, I _A −0 = I _A , and it is considered as an internal failure. Both activate the protection operation to protect the buses 1-1 and 1-2.

(iii) If circuit breaker 7-1 is OFF and circuit breaker 7-2 is ON, as is clear by corresponding to case (ii), this applies to the busbar protection relay devices in areas C and B.
Both protect busbars 1-2 and 1-3, respectively.

(iv) The case where the circuit breakers 7-1 and 7-2 shown in FIG. 4c are both turned on will be explained. In this case, switches 8-1 and 8-2 in FIG. 3 are both turned on. In the case of ground faults F _A and F _B , the bus protection relay device in area C does not detect any differential current. Therefore, the operation of the bus protection relay devices in areas A and B is clear from the explanations in (i) and (ii).

Note that the current ΣI″ _B of the adder circuit 9-2, which is the differential output of the bus protection relay device in area C,
is ΣI″ _B = ΣI _A + ΣI _B , and in the case of ground fault F _A , I _A −0 = I _A , and for the bus protection relay device in area C, I _A +0 = I _A , and internal fault regarded as.

In case of ground fault F _B , ΣI″ _B = I _B + (−I _B ) =
0, and the differential current in region C becomes 0+0=0, which is regarded as an external failure.

Next, to explain the case of ground fault F _E shown in Figure 4c, ΣI _A = I _C , ΣI _B = 0, ΣI _C = -I _C , ΣI' _B = ΣI _A + ΣI _B + ΣI _C = I _C +0+(-I _C )=0 ΣI'' _B = ΣI _A +ΣI _B = I _C +0=I _C ΣI''' _B = ΣI _B +ΣI _C =0+(-I _C )=- _IC . Therefore, the bus protection relay device in area B is inoperative, and the bus protection relay device in area A is I _C + (-I _C ) =
The bus bar protection relay device in area C becomes inoperable as (-I _C )+I _C =0. In this way, when both circuit breakers 7-1 and 7-2 are on, area A,
Each bus protection relay device of B and C collectively connects bus 1-
Protect 1, 1-2 and 1-3.

In the description of the above embodiments, a ground fault is explained as a failure type, but of course, the same operation and effect can be achieved for a short circuit fault as well.

In the above embodiment, a case has been described in which there are three busbar connections, but even if there are two or more busbar connections, the same effects as in the above embodiment can be achieved.

Furthermore, when the present invention is applied to a device whose differential characteristic has a ratio differential characteristic, as shown in FIG.
A maximum value suppression circuit may be provided which inputs the currents ΣI _A and ΣI _C via the switches 8-1 and 8-2 and obtains a suppression input for its own device. This enables the same processing as when the input terminal of the own device is increased by one terminal.
In terms of differential characteristics, the same effects as in the above embodiments are achieved.

As described above, according to the present invention, since the differential currents of the own device and other devices are sent and received as conditions for failure determination, when a busbar is connected via a circuit breaker, both ends of the circuit breaker Even if a current transformer is not installed in the system, it is possible to respond correctly to a failure, which has the effect of reducing the cost of the entire system.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional busbar protection relay device, FIG. 2 is a busbar connection diagram, and FIG. 3 is a block diagram of a busbar protection relay device according to an embodiment of the present invention.
4a to 4c are busbar connection diagrams, and FIG. 5 is a block diagram of a busbar protection relay device showing another embodiment of the present invention. 1-1 to 1-3...Bus line, 5,9-1 to 9-4...
Addition circuit, 6, 10...Level detection circuit, 8-1,
8-2...Switch. In addition, in the figures, the same reference numerals indicate the same parts.

Claims (1)

[Scope of Claims] 1. A switch that opens and closes in conjunction with the on/off of a circuit breaker that connects the bus bar of its own protection area to the bus bar of another protection area, and a plurality of lines connected to the bus bar of its own protection area. a first differential circuit that detects the sum of the current flowing in the first differential circuit; a second differential circuit that adds the total sum of current flowing through the line;
A bus protection relay device equipped with a level detection circuit that detects the output level of a differential circuit and determines a failure. 2. The busbar protection relay device according to claim 1, further comprising a maximum value suppression circuit that uses the output of the switch as a protection operation suppression input.